The device is particularly applicable to the junction between a chamber for cooling particles by indirect heat exchange with a combustion gas and a duct for recycling said particles to the hearth of a boiler, for example in an installation implementing the method described in patent document FR-B-2323101. The boiler may be a solid fuel boiler, in particular a coal fired boiler, burning particles in a flowing fluidized bed, or it may possibly be a liquid fuel boiler.
The prior art device is constituted by a metal bellows interconnecting either the outlet orifice of the cooling chamber and the end of the recycling duct, or else two portions of said duct. However, the inside of the bellows fills up with particles relatively quickly such that after a farily short length of time it is no longer capable of absorbing expansion, and leaks appear.
The object of the present invention is to provide a device for sealing and absorbing differential expansion which is capable of operating over very long periods of time without deteriorating, and which absorbs differential expansion equally well in all three dimensions.